Ovum Pick Up

Ovum Pick-Up (OPU) stands for oocyte collection and refers to the recovery (flushing) of oocytes from the mare. It is the first step in embryo production. In the oocyte collection technique, an ultrasound probe is placed inside the vagina of a sedated mare to visualize the ovarian follicles and correctly position the ovary. A needle is then inserted through the vaginal wall into individual follicles, where gentle suction is applied to retrieve the oocytes. The number of oocytes collected varies depending on the mare and each aspiration attempt. At our center, the average oocyte recovery rate per donor mare is 66%.

For on-site oocyte collection, mares are housed at our Equine Biotechnology Center, where we collect immature oocytes that require artificial maturation in an incubator before being used in ICSI.

Each situation is unique, and the decision to perform OPU is made in consultation with one of our veterinarians. After collection, the oocytes can either undergo ICSI in our lab or be shipped to a lab of your choice (advance notice is required, and shipping will be arranged via a commercial airline).

Your mare must arrive by the day of the OPU at the latest. If you are traveling from a distance, we recommend allowing her to stay overnight until the following day.

You can also board your mare at InnovumLab for an extended period. The frequency of OPU depends on the individual mare, but on average, it can be performed approximately every three weeks. Our priority is the well-being of the mares, so we ensure they spend most of the day outdoors with carefully selected herd mates, have ad libitum access to high-quality hay or silage, and receive concentrates enriched with minerals and vitamins to support reproductive health.

Immature oocytes can be collected via OPU by a veterinarian located closer to your mare and shipped to InnovumLab for sperm injection (ICSI). Your attending veterinarian will package the collected oocytes in a special medium and arrange for transport to our facility.

Our laboratory accepts off-site immature oocytes from Monday to Wednesday. They must be shipped in an appropriate container that maintains a temperature of approximately 22°C, using the correct media, and ideally within 24 hours of collection.

Equine embryo production using OPU and ICSI can be performed year-round, with no seasonal impact on embryo rates. OPU offers several benefits, especially for high-level competition mares with busy schedules, as it eliminates the need for repeated scans and the time involved with AI and ET.

Mares with a history of reproductive problems or other infertility challenges can also benefit from OPU/ICSI to improve fertility. Additionally, OPU is ideal when semen from a specific stallion is limited due to infertility or death, as only a small portion of a frozen semen straw is needed for ICSI.

OPU & ICSI are also highly effective for producing frozen embryos, as ICSI-produced embryos have a significantly higher post-thaw pregnancy rate compared to conventionally flushed and frozen embryos. Furthermore, it is possible to determine the sex of ICSI-produced embryos before freezing and transferring.

It is important to understand that, like many veterinary procedures, OPU carries some risks; however, these risks are generally very low. Possible complications include: Bleeding (rectal, vaginal or ovarian), rectal tears, rectal or ovarian abscesses, and peritonitis – which in the worst-case scenario can lead to death of the mare. The risk for serious complications is less than 1%. To minimize the risks associated with OPU, your mare will receive a long-acting antibiotic after the procedure as a preventative measure, along with flunixin to reduce discomfort and inflammation.

There is a higher early embryonic mortality following the transfer of ICSI embryos than with normal ET.

InnovumLab only works with experienced professionals who assess these risks, and if necessary will stop the procedure.

Before discharge, our vets will provide you with detailed instructions on what to monitor.

Please note that the mare must rest for at least 2–3 hours after OPU before she can be taken home. She will only be released once she is fully awake and showing signs of appetite. However, we recommend that the mare stay overnight after the procedure to be monitored.

After OPU, your mare can resume training after three days; however, starting with light exercise for a few days is recommended.